Fire fighting practice, in the case of forest fires or grass fires, sometimes involves the use of extensive lengths of fire hose. Commonly, one hose is connected to a water pump located a safe distance away from the fire source. Additional sections of hose are successively added, in series one after another, to form a hose system having a sufficient length to reach the fire. Often several sections of hose must be used.
Each hose section has metal threaded couplings on its ends for threaded connection with metal couplings on other hose sections, i.e., a male threaded coupling on the end of one hose section will be threaded into a female threaded coupling on the end of the next hose section. The hose section nearest the fire will have a water discharge nozzle screwed thereon.
During the course of a forest fire fighting operation it will be necessary from time to time to add sections of fire hose to the last hose section (i.e., the section nearest the blaze) in order to be able to move the water discharge nozzle to different places where the fire may be spreading. When adding a new section of hose to the last hose section it is necessary to first disconnect the water discharge nozzle, and to then screw on the new hose section to the last hose section, and to then screw the nozzle onto the end of the newly-added hose section. During this process it is desirable that the water flow through the connected hoses be temporarily halted. It is also desirable that the connected hoses remain filled with water during the hose connection process in order that the hose system be ready for resumption of the fire fighting process as soon as possible after reconnection of the water discharge nozzle to the new hose section.
Under preferred practice water flow through the water hose system is temporarily interrupted by cutting off the water flow at the last hose section, not back at the water pump. This cut-off process is often accomplished with the use of a hose clamp applied to the last section of hose near one of its metal couplings. The water discharge nozzle and hose couplings are disconnected and connected, with the clamp tightened down to completely restrict water flow through the last (final) hose section.
One known hose clamp used with fire hoses is a scissors clamp that, in practice, does not usually completely interrupt the water flow. Another prior art clamp used with fire hoses is a screw-operated device that requires the operator to stand on a special foot plate in order to manually rotate the screw.
The present invention is directed to a hose clamp of the screw-operated type. The clamp is designed so that it can be operated by one person solely with his two hands; he is not required to use his feet. A major aim of the invention is to provide a clamp that will completely cut off the water flow, even when relatively high water pressures are being used, e.g., 250 p.s.i. dynamic pressure.
Another object of the invention is to provide a clamp that will achieve a shut-off action in a reasonably short time span, but without subjecting the hose system to damaging water hammer effects.
A further object of the invention is to provide a clamp that will exert a hose-pinching action without crimping or otherwise cutting into the hose wall so as to prematurely shorten the hose service life.
An additional object of the invention is to provide a clamp that can be attached to the hose, then operated to interrupt water flow through the hose, and then removed from the hose, while the firefighter is wearing gloves; i.e., the firefighter is not required to remove his gloves while he is manipulating the hose clamp.
A further object of the invention is to provide a clamp that is relatively light in weight for easy handling or manipulation.
In one of its forms a clamp constructed according to the invention comprises a U-shaped guide structure for slidably supporting a movable jaw; a manual screw extends from that jaw through a nut in the central wall of the U-shaped structure, such that rotation of the screw drives the movable jaw toward or away from a stationary jaw that extends across the ends of the guide structure walls. Advancement of the movable jaw toward the stationary jaw causes the two jaws to cooperatively exert a squeezing action on a flexible water hose that extends through the intervening space between the two jaws. The movable jaw is advanced far enough that opposed sections of the water hose wall are flattened against one another so as to completely shut off the flow of water through the hose.
The stationary jaw is hingedly attached to one leg of the U-shaped guide structure so that it can be swung away from the movable jaw, thus opening a path for removal of the hose from the jaw space or insertion of another hose section into the jaw space.
The clamp is designed for easy operation and complete shut-off of the water flow through the hose section being gripped by the clamping jaws.